Dynamic Generation of Interface Section
Having to cut and paste the declaration from the implementation section to the interface (or vice versa) is totally unnecessary and complete violation of DRY. (I realize this can be automated somewhat by declaring first in Interface section and then using Ctrl+Shift+C).
There should be an option to have the interface section generated completely from the declarations in the implementation by declaring the visibility of the method using keywords such as private; e.g.
procedure TMyUnit.SetSomePropValue(value: integer); private;
Failing that - at the every least - the IDE should automatically propogate changes made to the name or parameters of a method declaration in the interface or implementation section.